Five VPCs across projects require full connectivity; two VPCs use overlapping Class E subnets (240.0.0.0/16 and 240.128.0.0/24). No Class E ranges need inter‑VPC connectivity; all other subnets need connectivity. Which routing solution meets the requirements?

The correct solution uses Network Connectivity Center (NCC) with a mesh topology and an export exclude filter. NCC simplifies connectivity for multiple VPCs, especially across projects, by centralizing routing and eliminating the need for a full mesh of VPC Peering. The mesh topology ensures full connectivity between all spokes. The export exclude filter 240.0.0.0/4 correctly prevents the overlapping Class E subnets from being advertised, as they do not require inter-VPC connectivity. Firewall rules are always necessary for allowing traffic. VPC Network Peering in a full mesh (options 1 and 4) becomes complex and difficult to manage with five or more VPCs. Option 1's instruction to not import/export public IP routes is insufficient for Class E, which are reserved and not public. Option 4's exclude filter is correct, but peering is less scalable than NCC. Multi-NIC VMs (option 3) are an overly complex and inefficient solution for inter-VPC routing, introducing management overhead and potential bottlenecks.